Known in the past has been an internal combustion engine in which an NOX purification catalyst is arranged in an engine exhaust passage, a fuel reforming device for generating reformed gas containing hydrogen is provided, high temperature reformed gas containing hydrogen produced in the fuel reforming device is fed to the engine exhaust passage upstream of the NOX purification catalyst at the time of engine start, and the hydrogen in the supplied reformed gas is used to raise the NOX purification rate of the NOX purification catalyst (for example, see Japanese Unexamined Patent Publication No. 2010-270664).